In some applications such as in a motor vehicle, a single electrical power source is employed to energise multiple electrical loads each via its own output connection. An electronic smart switch module, e.g. comprising one or more pre-programmed semiconductor integrated circuit chips, may be employed to control switching of each of the loads between an ‘On’ (energised) state and an ‘Off’ (unenergised) state as required.
In the prior art, smart switch modules are known which are able to diagnose certain faults such as a short circuit connection, herein referred to as a ‘short’, to the power source leaving an output connection to a load in an ‘open load’ condition in which the load is unenergised.